Resin molded semiconductor device and method for manufacturing the same

ABSTRACT

A method for manufacturing a semiconductor chip ( 15 ) which is bonded on a die pad ( 13 ) of a leadframe, and inner leads ( 12 ) are electrically connected to electrode pads of the semiconductor chip ( 15 ) with metal fine wires ( 16 ). The die pad ( 13 ), semiconductor chip ( 15 ) and inner leads are molded with a resin encapsulant ( 17 ). However, no resin encapsulant ( 17 ) exists on the respective back surfaces of the inner leads ( 12 ), which protrude downward from the back surface of the resin encapsulant ( 17 ) so as to be external electrodes ( 18 ).

TECHNICAL FIELD

The present invention relates to a resin-molded semiconductor device, inwhich a semiconductor chip and a leadframe are molded with a resinencapsulant, and to a method for manufacturing such a device. Inparticular, the present invention relates to a device with the backsurface of the leadframe partially exposed out of the resin encapsulant.

BACKGROUND ART

In recent years, in order to catch up with rapidly advancing downsizingof electronic units, it has become increasingly necessary to packagesemiconductor components for each of these electronic units at a higherand higher density. Correspondingly, sizes and thicknesses ofsemiconductor components have also been noticeably reduced.

Hereinafter, a conventional resin-molded semiconductor device will bedescribed.

FIG. 23(a) is a plan view of a conventional resin-molded semiconductordevice, and FIG. 23(b) is a cross-sectional view of the conventionalresin-molded semiconductor device.

As shown in FIGS. 23(a) and 23(b), this conventional resin-moldedsemiconductor device is of the type including external electrodes on itsback surface.

The conventional resin-molded semiconductor device includes a leadframeconsisting of: inner leads 201; a die pad 202; and support leads 203 forsupporting the die pad 202. A semiconductor chip 204 is bonded onto thedie pad 202 with an adhesive, and electrode pads (not shown) of thesemiconductor to chip 204 are electrically connected to the inner leads201 with metal fine wires 205. And the die pad 202, semiconductor chip204, inner leads 201, support leads 203 and metal fine wires 205 aremolded with a resin encapsulant 6. In this structure, no resinencapsulant 206 exists on respective back surfaces of the inner leads201. In other words, the respective back surfaces of the inner leads 201are exposed and respective lower parts of the inner leads 201, includingthese exposed back surfaces, serve as external electrodes 207.

In such a resin-molded semiconductor device, the respective backsurfaces of the resin encapsulant 206 and those of the inner leads 201are both located in the same plane, and the die pad 202 is located abovethe inner leads 201. That is to say, by providing depressed portions 208for the support leads 203, the die pad 202 is elevated above the innerleads 201. Thus, after the device has been molded with the resinencapsulant 206, a thin layer of the resin encapsulant 206 is alsoformed on the back surface of the die pad 202. In FIG. 23(a), the resinencapsulant 206 is illustrated as being transparent such that the insideof the semiconductor device can be looked through. In FIG. 23(a), thesemiconductor chip 204 is indicated by the dashed line and theillustration of the metal fine wires 205 is omitted.

Also, conventionally, to secure a required standoff height from the backsurface of the resin encapsulant 206 in bonding the external electrodesto the electrodes of a motherboard such as a printed wiring board, onwhich a resin-molded semiconductor device is mounted, ball electrodes209 of solder are attached to the external electrodes 207 as shown inFIG. 24. After the standoff height has been secured by these ballelectrodes 209, the device is mounted onto the motherboard.

Hereinafter, a method for manufacturing the conventional resin-moldedsemiconductor device will be described with reference to the drawings.FIGS. 25 through 27 are cross-sectional views illustrating amanufacturing process for the conventional resin-molded semiconductordevice.

First, as shown in FIG. 25, a leadframe 210, including the inner leads201 and die pad 202, is prepared. It is noted that the die pad 202 isactually supported by the support leads, but the illustration of thesupport leads is omitted in FIG. 25. Depressed portions are formed inthe support leads and the die pad 202 is elevated above the plane onwhich the inner leads 201 are located. The leadframe 210 does notinclude any tie bar used for preventing the resin encapsulant fromflowing out during resin encapsulation.

Next, as shown in FIG. 26, the semiconductor chip 204 is bonded, with anadhesive, to the die pad 202 of the lead-frame prepared. This processstep is called “die bonding”.

Then, as shown in FIG. 27, the semiconductor chip 204, which has beenbonded onto the die pad 202, is electrically connected to the innerleads 201 via the metal fine wires 205. This process step is called“wire bonding”. As the metal fine wires 205, aluminum (Al) or gold (Au)fine wires may be appropriately used, for example.

Subsequently, as shown in FIG. 28, the die pad 202, semiconductor chip204, inner leads 201, support leads and metal fine wires 205 are moldedwith the resin encapsulant 206. In this case, the leadframe, on whichthe semiconductor chip 204 has been bonded, is introduced into a moldingdie assembly and transfer-molded. In particular, resin encapsulation isperformed with the back surface of the inner leads 201 in contact withan upper or lower die of the die assembly.

Finally, the ends 211 of the inner leads 201, protruding outward fromthe resin encapsulant 206, are cut off after the resin encapsulation. Byperforming this cutting process step, the end faces of the inner leads201 cut off are substantially flush with the side faces of the resinencapsulant 6 and the respective lower parts of the inner leads 201 areused as external electrodes 207.

In the manufacturing process of this conventional resin-moldedsemiconductor device, the resin encapsulant 206 might overflow from theedges of the inner leads 201, reach the back surfaces thereof andthereby form resin bur thereon (overflowing resin) during the resinencapsulation process step. Thus, a water jet process step is introducedfor blowing off the resin bur after the resin encapsulation process stepand before the process step of cutting off the inner leads 201.

Also, if necessary, ball electrodes of solder are formed on the lowersurfaces of the external electrodes 207, thereby completing theresin-molded semiconductor device shown in FIG. 24. As anotheralternative, a solder plating layer is sometimes formed instead of thesolder balls.

PROBLEMS TO BE SOLVED

The conventional resin-molded semiconductor device, however, has thefollowing drawbacks. First, since the lower surfaces of the externalelectrodes 207 are located in substantially the same plane as that ofthe resin encapsulant 206 on the back of the semiconductor device, nostandoff height from the resin encapsulant 206 can be obtained. Thus,the device must be mounted onto a motherboard with the ball electrodes209 of solder interposed therebetween. Accordingly, mounting cannot becarried out efficiently.

In addition, during the resin encapsulation step of the conventionalprocess for manufacturing a resin-molded semiconductor device, aleadframe, on which a semiconductor chip has been bonded, is introducedinto a molding die assembly and then molded with a resin by pressing theinner leads against the surface of the lower die such that the leadsclosely contact the die. Even so, there occurs a problem that the resinencapsulant reaches the back surface of the inner leads to form a resinbur (overflowing resin) on the surface of the external electrodes.

FIG. 30 is a partial plan view illustrating, on a larger scale, theexternal electrodes 207 and their surroundings on the back of thesemiconductor device as illustrated within the circle in FIG. 23(a). Asshown in FIG. 30, resin bur 206 a is sometimes formed on the respectivelower surfaces of the external electrodes 207 during the conventionalresin encapsulation process step. That is to say, the resin encapsulant206 reaches the lower surfaces of the external electrodes 207 to formthe resin bur 206 a thereon during the resin encapsulation process step.In other words, part of each external electrode 207 is buried within theresin encapsulant 206.

Thus, a water jet process step has heretofore been introduced to blowoff the resin bur 206 a on the external electrodes 207. However, such awater jet process step is very troublesome and is contradictory to thedemand on a process simplification to manufacture resin-moldedsemiconductor devices in high volume or on a reduction in number ofprocess steps. That is to say, the formation of the resin bur is anon-negligible factor interfering with such simplification ofmanufacturing process.

A leadframe for a general-purpose resin-molded semiconductor devicecurrently used is ordinarily made of copper (Cu) or Alloy 42. Thismaterial is plated with nickel (Ni) as an undercoat layer and thenplated with palladium (Pd) and gold (Au). In the conventional process,however, if the resin bur is blown off with high-pressure water jetduring the water jet process step introduced to remove the resin bur,then not only the resin bur, but also soft metal plating peel off withthe water jet. Also, serious quality control problems, like depositionof impurities, might happen.

To avoid this problem, various measures can be taken, e.g., theleadframe may be plated after the water jet process step is over.However, in such a case, a metal layer preplating treatment (or apreparatory plating treatment) cannot be performed, i.e., the leadframecannot be plated prior to the resin encapsulation process step.Accordingly, the plating process step cannot be performed efficiently,thus further interfering with the simplification of manufacturingprocess. Also, such a measure is not preferable in terms of thereliability of a resin-molded semiconductor device, either.

An object of this invention is providing a resin-molded semiconductordevice and a method for manufacturing the same, which can meet thedemand on a simplified manufacturing process by suppressing theformation of resin bur on the back of a leadframe or by ensuring astandoff height of external electrodes from a resin encapsulant during aresin encapsulation process step.

DISCLOSURE OF INVENTION

In order to achieve this object, the present invention discloses aresin-molded semiconductor device formed by using a seal tape forpreventing the overflow of a resin during resin encapsulation and amethod for manufacturing a resin-molded semiconductor device using aseal tape.

A resin-molded semiconductor device according to the present inventionincludes: a semiconductor chip having electrode pads; inner leads;connection members for electrically connecting the electrode pads of thesemiconductor chip to the inner leads; and a resin encapsulant formolding the semiconductor chip, inner leads and connection memberstogether. The lower part of each said inner lead, including at leastpart of the back surface thereof, functions as an external electrode.And the external electrode protrudes downward from the back surface ofthe resin encapsulant.

In this structure, since the external electrode of the inner leadprotrudes from the resin encapsulant, a standoff height can be securedfor the external electrode. That is to say, in this structure, the innerleads can be directly connected, as external terminals, onto amotherboard without providing any ball electrodes for the externalelectrodes. As a result, the first object is accomplished.

The resin-molded semiconductor device may further include: a die pad forsupporting the semiconductor chip thereon; and support leads forsupporting the die pad. Each said support lead may include a depressedportion for elevating the die pad above the inner leads.

In such an embodiment, the resin encapsulant exists under the die pad,thus increasing the force of the resin encapsulant holding the die padand semiconductor chip. In addition, since the die pad is slightlyelevated only by the depth of the depression of the support leads, thestructure of the resin-molded semiconductor device can be kept thinwithout increasing the thickness of the resin-molded semiconductordevice so much.

In the resin-molded semiconductor device, a protrusion height of theexternal electrodes as measured from the back surface of the resinencapsulant is preferably in the range from about 10 μm to about 40 μm.

In such an embodiment, the force of the resin encapsulant holding theinner leads is not weakened so much and the external electrodes can bemade to function as external terminals.

A basic method for manufacturing a resin-molded semiconductor deviceaccording to the present invention includes: a first step of preparingmolding die assembly, semiconductor chip and peripheral member; a secondstep of attaching a seal tape to between the peripheral member and thedie assembly such that the seal tape adheres to part of a surface of theperipheral member; a third step of encapsulating the semiconductor chipand the peripheral member, except for at least the part of the surfacethereof, within a resin encapsulant with the seal tape attached; and afourth step of removing the seal tape after the third step has beenperformed. After the fourth step has been performed, at least the partof the surface of the peripheral member is exposed out of the resinencapsulant.

According to this method, if there is any part to be exposed withoutfail in the peripheral member, a structure with that part exposed out ofthe resin encapsulant can be obtained by adhering the seal tape to thatpart of the peripheral member in the second step. Also, since no resinbur is formed on that part of the peripheral member, either,conventionally required process steps, like water jet, can beeliminated. As a result, the manufacturing process can be simplified,and therefore, the first object is accomplished.

In the basic method for manufacturing a resin-molded semiconductordevice, the first step may include: a first sub-step of preparing, asthe peripheral member, a leadframe including inner leads and a regionfor supporting the semiconductor chip thereon; a second sub-step ofbonding the semiconductor chip onto the region of the leadframe forsupporting the semiconductor chip thereon; and a third sub-step ofelectrically bonding the semiconductor chip to the inner leads. In thesecond step, the seal tape may be adhered to the back surfaces of theinner leads.

According to this method, a resin-molded semiconductor device, in whicha semiconductor chip, connected to a lead-frame, is provided within aresin encapsulant, is obtained. Also, the back surfaces of the innerleads never fail to be exposed out of the resin encapsulant.Furthermore, by regulating the pressure of the inner leads against theseal tape, the protrusion height of the inner leads as measured from theback surface of the resin encapsulant, i.e., the standoff height of theinner leads, can be adjusted. Accordingly, a resin-molded semiconductordevice, attaining the effects of the first resin-molded semiconductordevice described above, can be formed easily.

In the method for manufacturing a resin-molded semiconductor deviceincluding the leadframe, in the first sub-step of the first step, a diepad may be formed as the region for supporting the semiconductor chipthereon. Support leads may be formed for supporting the die pad. And adepressed portion for elevating the die pad above the inner leads may beformed in each said support lead. In the second sub-step of the firststep, the semiconductor chip may be bonded onto the die pad. In thethird sub-step of the first step, the semiconductor chip, which has beenbonded onto the die pad, may be electrically bonded to the inner leadsvia metal fine wires. And in the second step, the seal tape may beadhered only to the back surfaces of the inner leads in the leadframe.

According to this method, the resin encapsulant can exist under the backof the die pad without increasing the total thickness of theresin-molded semiconductor device so much. As a result, the force of theresin encapsulant holding the die pad can be increased and a thinnerresin-molded semiconductor device can be formed easily.

The method for manufacturing a resin-molded semiconductor deviceincluding the leadframe may further include the step of cutting off partof each said inner lead laterally protruding out of the resinencapsulant such that end faces of the inner leads are substantiallyflush with the side faces of the resin encapsulant after the fourth stephas been performed.

According to this method, a laterally protruding portion can beeliminated from each inner lead. As a result, a resin-moldedsemiconductor device with a reduced area can also be formed.

In the method for manufacturing a resin-molded semiconductor deviceincluding the leadframe, in the first sub-step of the first step, theleadframe prepared may have been plated with nickel (Ni), palladium (Pd)and gold (Au) layers.

According to this method, plated layers of quality can be formed bypre-plating, and the use of a seal tape can eliminate additional processsteps for removing resin bur, such as a water jet process step, whichare usually performed after resin encapsulation. Accordingly, even whenresin bur should be removed, the plated layers do not peel off.

In the method for manufacturing a resin-molded semiconductor deviceincluding the leadframe, in the second step, the seal tape attached mayhave such a thickness as corresponding to a predetermined value, whichis equal to the height of the lower surfaces of the inner leadsprotruding downward from the back surface of the resin encapsulant afterthe resin encapsulation.

According to this method, the protrusion height of the inner leads canbe easily adjusted based on the thickness of the seal tape. Accordingly,not only the force of the resin encapsulant holding the inner leads, butalso the standoff height provided for making the lower part of eachinner lead function as an external terminal can be controlled atrespectively adequate values.

In the basic method for manufacturing a resin-molded semiconductordevice, the first step may include: a first sub-step of preparing asubstrate as the peripheral member, the upper surface of the substratebeing provided with interconnects, the back surface of the substratebeing provided with external electrodes to be connected to theinterconnects; a second sub-step of bonding the semiconductor chip ontothe upper surface of the substrate; and a third sub-step of electricallyconnecting the semiconductor chip to the interconnects on the uppersurface of the substrate via connection members. In the second step, theseal tape may be adhered at least to the external electrodes.

According to this method, a resin-molded semiconductor device of asubstrate-bonded type, in which external electrodes are exposed out ofthe resin encapsulant without fail, can be formed.

In the basic method for manufacturing a resin-molded semiconductordevice, the first step may include: a first sub-step of preparing atleast a radiator plate as the peripheral member; and a second sub-stepof mounting the semiconductor chip on the radiator plate. In the secondstep, the seal tape may be attached to the back surface of the radiatorplate.

According to this method, a resin-molded semiconductor device includinga radiator plate with good radiation properties, in which no resinencapsulant overflows to reach the back of the radiator plate, can beformed.

In the method for manufacturing a resin-molded semiconductor deviceincluding the radiator plate, in the first substep of the first step, aleadframe including leads and a bed may be further prepared as theperipheral member. In the second sub-step of the first step, thesemiconductor chip may be bonded onto the bed and then the bed may bemounted onto the radiator plate, thereby mounting the semiconductor chipover the radiator plate.

According to this method, a resin-molded semiconductor device includinga radiator plate can be formed easily by using a leadframe.

In the basic method for manufacturing a resin-molded semiconductordevice, in the first step, a lead assembly, including inner and outerleads, may be prepared as the peripheral member. In the second step, theseal tape may be adhered to between the inner leads and the molding dieassembly so as to be attached to part of the surface of each said innerlead. In the third step, all the members, except for at least the partof the surface of each said inner lead, may be encapsulated within theresin encapsulant with the seal tape attached, thereby forming a resinpackage including an opening and a recess within the opening. The methodmay further include, posterior to the fourth step, the steps of:mounting the semiconductor chip having the electrode pads into therecess of the resin package; electrically connecting the electrode padsof the semiconductor chip to the inner leads via connection members; andsealing the opening with a sealing member. After the fourth step hasbeen performed, at least the part of the surface of each said inner leadmay be exposed out of the resin encapsulant.

According to this method, it is possible to form easily a resin-moldedsemiconductor device, which a solid-state imaging device or the like,requiring an overlying free space, is built in. In such a case, aconnection portion between an inner lead and the semiconductor chip canbe exposed out of the resin encapsulant without fail.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1(a) and 1(b) are respectively plan view and cross-sectional viewof a resin-molded semiconductor device according to a first embodimentof the present invention, in which a resin encapsulant is illustrated asbeing transparent.

FIG. 2 is a cross-sectional view illustrating the process step ofpreparing a leadframe during a manufacturing process of the resin-moldedsemiconductor device in the first embodiment.

FIG. 3 is a cross-sectional view illustrating the process step ofbonding a semiconductor chip onto a die pad during the manufacturingprocess of the resin-molded semiconductor device in the firstembodiment.

FIG. 4 is a cross-sectional view illustrating the process step offorming metal fine wires during the manufacturing process of theresin-molded semiconductor device in the first embodiment.

FIG. 5 is a cross-sectional view illustrating the process step ofplacing a seal tape under the leadframe during the manufacturing processof the resin-molded semiconductor device in the first embodiment.

FIG. 6 is a cross-sectional view illustrating a resin encapsulationprocess step during the manufacturing process of the resin-moldedsemiconductor device in the first embodiment.

FIG. 7 is a cross-sectional view of the resin-molded semiconductordevice after the process step of cutting off the ends of the inner leadsis finished during the manufacturing process of the resin-moldedsemiconductor device in the first embodiment.

FIG. 8 is a partial bottom view of the resin-molded semiconductor deviceformed by the manufacturing process of the resin-molded semiconductordevice in the first embodiment.

FIG. 9 is a cross-sectional view of a resin-molded semiconductor deviceof a substrate-bonded type according to a second embodiment of thepresent invention.

FIGS. 10(a) and 10(b) are cross-sectional views illustrating the processstep of bonding a semiconductor chip onto the substrate with metal finewires and the process step of mounting a semiconductor chip onto thesubstrate with bumps, respectively, during a manufacturing process ofthe resin-molded semiconductor device in the second embodiment.

FIG. 11 is a cross-sectional view illustrating a resin encapsulationprocess step during the manufacturing process of the resin-moldedsemiconductor device in the second embodiment.

FIG. 12 is a cross-sectional view of a resin-molded assembly after theseal tape has been removed during the manufacturing process of theresin-molded semiconductor device in the second embodiment.

FIG. 13 is a cross-sectional view of a resin-molded semiconductor deviceincluding a radiator plate according to a third embodiment of thepresent invention.

FIG. 14 is a cross-sectional view illustrating the process step ofpreparing a leadframe during a manufacturing process of the resin-moldedsemiconductor device in the third embodiment.

FIG. 15 is a cross-sectional view illustrating the process step ofbonding a semiconductor chip onto a radiator plate and forming metalfine wires during the manufacturing process of the resin-moldedsemiconductor device in the third embodiment.

FIG. 16 is a cross-sectional view illustrating the process step ofplacing a seal tape under the radiator plate and the leadframe duringthe manufacturing process of the resin-molded semiconductor device inthe third embodiment.

FIG. 17 is a cross-sectional view illustrating a resin encapsulationprocess step during the manufacturing process of the resin-moldedsemiconductor device in the third embodiment.

FIG. 18 is a cross-sectional view of the resin-molded semiconductordevice after the seal tape has been removed during the manufacturingprocess of the resin-molded semiconductor device in the thirdembodiment.

FIG. 19 is a cross-sectional view of a resin-molded semiconductor deviceas a CCD package according to a fourth embodiment of the presentinvention.

FIG. 20 is a cross-sectional view illustrating a resin encapsulationprocess step during a manufacturing process of the resin-moldedsemiconductor device in the fourth embodiment.

FIG. 21 is a cross-sectional view illustrating the process step ofremoving a seal tape after the resin encapsulation during themanufacturing process of the resin-molded semiconductor device in thefourth embodiment.

FIG. 22 is a cross-sectional view illustrating the process step offorming metal fine wires and sealing with seal glass during themanufacturing process of the resin-molded semiconductor device in thefourth embodiment.

FIGS. 23(a) and 23(b) are respectively plan view and cross-sectionalview of a conventional resin-molded semiconductor device of the typeincluding external electrodes on its back.

FIG. 24 is a cross-sectional view of a conventional resin-moldedsemiconductor device ensuring a standoff height by providing ballelectrodes for the external electrodes.

FIG. 25 is a cross-sectional view illustrating the process step ofpreparing a leadframe during a conventional manufacturing process of theresin-molded semiconductor device.

FIG. 26 is a cross-sectional view illustrating the process step ofbonding a semiconductor chip onto a die pad during the conventionalmanufacturing process of the resin-molded semiconductor device.

FIG. 27 is a cross-sectional view illustrating the process step offorming metal fine wires during the conventional manufacturing processof the resin-molded semiconductor device.

FIG. 28 is a cross-sectional view illustrating a resin encapsulationprocess step during the conventional manufacturing process of theresin-molded semiconductor device.

FIG. 29 is a cross-sectional view of the resin-molded semiconductordevice after the resin encapsulation during the conventionalmanufacturing process of the resin-molded semiconductor device.

FIG. 30 is a bottom view of the resin-molded semiconductor device formedby the conventional manufacturing process of the resin-moldedsemiconductor device.

BEST MODE FOR CARRYING OUT THE INVENTION EMBODIMENT 1

FIG. 1(a) is a plan view of a resin-molded semiconductor deviceaccording to a first embodiment, and FIG. 1(b) is a cross-sectional viewthereof taken along the line 1 b—1 b in FIG. 1(a). In FIG. 1(a), a resinencapsulant 17 is illustrated as being transparent, a semiconductor chip15 has a contour as indicated by the dashed line, and the illustrationof metal fine wires 16 is omitted.

As shown in FIGS. 1(a) and 1(b), the resin-molded semiconductor deviceof this embodiment includes a leadframe consisting of: inner leads 12; adie pad 13 for supporting the semiconductor chip thereon; and supportleads 14 for supporting the die pad 13. The semiconductor chip 15 isbonded on the die pad 13 with an adhesive, and electrode pads (notshown) of the semiconductor chip 15 are electrically connected to theinner leads 12 with metal fine wires 16. And the inner leads 12, die pad13, support leads 14, semiconductor chip 15 and metal fine wires 16 areencapsulated within the resin encapsulant 17. Also, the die pad 13 iselevated by depressed portions 19 of the support leads 14 so as to belocated above the inner leads 12. Accordingly, after the chip, frame andso on have been molded with the resin encapsulant 17, a thin layer ofthe resin encapsulant 17 exists under the back surface of the die pad13.

Hereinafter, the features of the resin-molded semiconductor deviceaccording to this embodiment will be described. No resin encapsulant 17exists on the respective lower parts of the inner leads 12. In otherwords, the respective lower surfaces of the inner leads 12 are exposed,and are used as interconnection with a motherboard. That is to say, therespective lower parts of the inner leads 12 function as externalelectrodes 18. In addition, virtually no resin burr, which ordinarilysticks out during a resin encapsulation process step, exists on theexternal electrodes 18. And the external electrodes 18 slightly protrudedownward from the back surface of the resin encapsulant 17. The externalelectrodes 18 can be easily formed in such a shape by the manufacturingprocess described later so as to protrude downward and have no resinburr thereon.

In the resin-molded semiconductor device of this embodiment, no outerleads, which function as external electrode terminals in manyconventional structures, exist beside the inner leads 12. Instead, thelower part of each inner lead 12, including the lower and side facesthereof, functions as an external electrode 18. Accordingly, such astructure contributes to downsizing of a semiconductor device. Moreover,since no resin burr exists on the respective lower surfaces of the innerleads 12, i.e., the lower surfaces of the external electrodes 18, theelectrodes of the motherboard can be bonded to these external electrodes18 with more reliability. Furthermore, the external electrodes 18 areformed to protrude from the plane of the resin encapsulant 17. Thus, astandoff height, which should be secured in bonding the externalelectrodes to the electrodes of the motherboard during mounting of theresin-molded semiconductor device onto the motherboard, has already beenprovided for the external electrodes 18. Accordingly, the externalelectrodes 18 can be used as external terminals as they are. Also,unlike the conventional process, there is no need to attach solder ballsto the external electrodes 18 during mounting of the device onto themotherboard. Therefore, this method is advantageous in the number andcost of manufacturing process steps.

In addition, the die pad 13 is elevated above the inner leads 12 and athin layer of the resin encapsulant 17 exists on the back of the die pad13. As a result, the reliability of the resin-molded semiconductordevice improves.

In this embodiment, the die pad 13 is provided for supporting thesemiconductor chip 15 thereon. Alternatively, even if it were not forthe die pad 13, the semiconductor chip still could be supported by therespective insulated ends of the inner leads or mounted on a plastictape. That is to say, the die pad 13 is not always required, and thisembodiment is applicable to a leadframe without a die pad.

Also, in this embodiment, the metal fine wires 16 are used as means forelectrically connecting the electrodes of the semiconductor chip 15 tothe inner leads 12. Alternatively, the electrodes of the semiconductorchip 15 may be electrically connected to the inner leads 12 by flip-chipbonding (i.e., with bumps interposed therebetween) or direct bonding(i.e., by forming a eutectic alloy).

Next, a method for manufacturing the resin-molded semiconductor deviceof this embodiment will be described with reference to the drawings.FIGS. 2 through 7 are cross-sectional views illustrating a manufacturingprocess of the resin-molded semiconductor device of this embodiment.

First, in the process step shown in FIG. 2, a lead-frame 20, includinginner leads 12 and a die pad 13 for supporting a semiconductor chipthereon, is prepared. Although the die pad 13 is actually supported bysupport leads, the support leads are not illustrated in FIG. 2 becausethe leads are not included in this cross section. Also, a depressedportion is formed in each of these support leads, thereby the die pad 13is elevated above the plane on which the inner leads 12 are located. Theleadframe 20 prepared is not provided with tie bars used for stoppingthe outflow of a resin encapsulant during resin encapsulation.

The leadframe 20 of this embodiment is formed by plating a frame made ofcopper (Cu) with the three metal layers of: an undercoat nickel (Ni)layer; a palladium (Pd) layer plated thereon; and an outermost thin gold(Au) layer. Alternatively, the leadframe 20 may be made of any rawmaterial other than copper (Cu), e.g., Alloy 42. Also, the leadframe 20may be plated with any noble metals other than nickel (Ni), palladium(Pd) and gold (Au). Furthermore, the number of plated layers does nothave to be three.

Next, in the process step shown in FIG. 3, a semiconductor chip 15 ismounted and bonded, with an adhesive, onto the die pad of the leadframeprepared. This process step is so-called “die bonding”. It should benoted that any support member other than a leadframe may be used tosupport the semiconductor chip. For example, a TAB tape or a substratemay also be used.

Then, in the process step shown in FIG. 4, the semiconductor chip 15,which has been bonded onto the die pad 13, is electrically bonded to theinner leads 12 with metal fine wires 16. This process step is so-called“wire bonding”. The metal fine wires may be made of an appropriatelyselected material such as aluminum (Al) or gold (Au). Optionally, thesemiconductor chip 15 may be electrically connected to the inner leads12 via bumps or the like, not the metal fine wires 16.

Subsequently, in the process step shown in FIG. 5, a seal tape 21 isattached to the respective back surfaces of the inner leads 12 with thesemiconductor chip 15 bonded onto the die pad 13 of the leadframe.

The seal tape 21 is used as a sort of mask for preventing the resinencapsulant from overflowing and reaching the respective lower surfacesof the inner leads 12 during resin encapsulation. The existence of theseal tape 21 can prevent resin burr from being formed on the backsurfaces of the inner leads 12. The seal tape 21 attached to the innerleads 12 and so on may be any resin-based tape, which is mainly composedof polyethylene terephthalate, polyimide, polycarbonate or the like, canbe easily peeled after the resin encapsulation and has some resistanceto an elevated-temperature environment during the resin encapsulation.In this embodiment, a tape mainly composed of polyethylene terephthalateis used and the thickness thereof is 50 μm.

In this embodiment, the seal tape 21 is attached to the entire backsurface of the leadframe, but is adhered only to the surfaces of theinner leads 12 of the leadframe. That is to say, the seal tape 21 doesnot adhere to the back surface of the die pad 13, which is elevated bythe depressed portions of the support leads. Alternatively, theradiation properties of the die pad 13 may be increased by adhering theseal tape 21 to the back surface of the die pad 13 and then peeling theseal tape 21 off to expose the back surface of the die pad 13 after theresin encapsulation step.

Then, in the process step shown in FIG. 6, the lead-frame, on which thesemiconductor chip 15 has been bonded and to which the seal tape 21 hasbeen attached, is introduced into a die assembly. And a resinencapsulant 17 is poured into the die assembly to mold the chip, frameand so on with the encapsulant 17. In this case, resin encapsulation isperformed while pressing downward the ends 22 of the inner leads 12 ofthe leadframe with the dies such that the resin encapsulant 17 does notreach the respective lower surfaces of the inner leads 12. The resinencapsulation is also performed with the seal tape 21 on the back of theinner leads 12 pressed against the face of the die.

Finally, in the process step shown in FIG. 7, the seal tape 21, whichhas been attached to the respective back surfaces of the inner leads 12,is peeled off and removed, thereby forming external electrodes 18,protruding from the back surface of the resin encapsulant 17. Then, theends of the inner leads 12 are cut off to be substantially flush withthe side faces of the resin encapsulant 17, thereby completing aresin-molded semiconductor device such as that shown in FIG. 7.

FIG. 8 is a partial bottom view of the resin-molded semiconductor deviceof this embodiment, illustrating respective parts of the externalelectrodes 18 on a larger scale. As shown in FIG. 8, in this embodiment,the formation of resin bur on the back and side faces of the inner leads12, i.e., on the surfaces of the external electrodes 18, can beprevented. This is because the resin encapsulation process step isperformed with the seal tape 21 adhered to the back surface of theleadframe. Also, unlike a conventional manufacturing process, it ispossible to prevent the resin encapsulant 17 from reaching the surfacesof the external electrodes 18 and part of the external electrodes 18from being buried in the resin encapsulant 17.

According to the manufacturing method of this embodiment, the seal tape21 is attached in advance to the respective back surfaces of the innerleads 12 before the resin encapsulation process step. Thus, the resinencapsulant 17 cannot reach, and no resin burr is formed on, the backsurfaces of the inner leads 12 functioning as external electrodes.Accordingly, resin burr, formed on the inner leads, need not be removedtherefrom using water jet or the like, unlike a conventional method formanufacturing a resin-molded semiconductor device with the lowersurfaces of inner leads entirely exposed. That is to say, since thistroublesome step of deburring can be omitted, this process is simpleenough to mass-produce a great number of resin-molded semiconductordevices. In addition, peeling of metal plated layers such as nickel(Ni), palladium (Pd) and gold (Au) on the leadframe, which might happenduring the conventional deburring process step using water jet, forexample, can be eliminated. For that reason, the leadframe can be platedin advance with these metal layers before the resin encapsulationprocess step.

In addition, since the external electrodes 18 formed by themanufacturing process of this embodiment protrude from the resinencapsulant 17, the external electrodes 18 can be used as externalterminals as they are, without providing solder balls as in aconventional process.

Although the step of deburring using water jet can be omitted, the stepof attaching the seal tape should be additionally performed in thisembodiment. However, the step of attaching the seal tape 21 is morecost-effective than the water jet process step. And it is easier tocontrol the former process step than the latter. Accordingly, theprocess can be simplified without fail. Among other things, the methodof this embodiment is particularly advantageous in that attaching theseal tape can eliminate the water jet process step conventionallyrequired, which has brought about various quality-control problems likepeeling of metal plated layers from the leadframe and deposition ofimpurities thereon. Thus, in this embodiment, the plated metal layersare much less likely to peel off. Also, it is true that resin burr stillmay be formed in this embodiment depending on the attachment state ofthe seal tape. Even so, the resulting resin burr is very thin, and canbe easily removed with water jet at a low water pressure. Accordingly,should such a water jet process step be required, peeling of the metalplated layers still can be prevented. And there is no problem if theleadframe is plated with these metal layers beforehand.

It should be noted that a level difference is formed between therespective back surfaces of the inner leads 12 and that of the resinencapsulant 17 as shown in FIG. 6. This is because the seal tape 21softens and thermally shrinks owing to the heat applied by the moltenresin encapsulant during the resin encapsulation step, and the innerleads 12 are strongly forced into the seal tape 21. Accordingly, in thisstructure, the back surfaces of the inner leads 12 protrude from that ofthe resin encapsulant 17. As a result, a stand-off height of theexternal electrodes 18, or the respective lower parts of the inner leads12, can be secured. Therefore, these protruding external electrodes 18can be used as external terminals as they are.

The height of the level difference between the respective back surfacesof the inner leads 12 and that of the resin encapsulant 17 can becontrolled based on the thickness of the seal tape 21 attached beforethe step of encapsulating. For example, in this embodiment, since thethickness of the seal tape 21 is 50 μm, the height of the leveldifference, i.e., the protrusion height of the external electrodes 18,is usually about one-half of the thickness, and 50 μm at its maximum.That is to say, the height of a portion of the seal tape 21 upwardlyforced as measured from the back surfaces of the inner leads 12 isdetermined depending on the thickness of the seal tape 21. In otherwords, the protrusion height of the external electrodes 18 can beself-controlled by the thickness of the seal tape 21, thus facilitatingthe manufacturing. The protrusion height of the external electrodes 18can be controlled only by adjusting the thickness of the seal tape 21during a mass production process, and there is no need to provide anadditional process step separately. Accordingly, the manufacturingmethod of this embodiment is extremely advantageous in terms of theprocess control cost. It should be noted that as for the seal tape 21 tobe attached, the hardness of a material used, the thickness and thethermal softening properties thereof can be determined depending on thedesired height of the level difference.

In the resin-molded semiconductor device of this embodiment, althoughthe resin encapsulant 17 exists on the back of the die pad 13 as shownin FIG. 2, the thickness thereof is equal to the elevated height of thedie pad 13, and is extremely small. Thus, the resin-molded semiconductordevice of this embodiment is substantially one-side-encapsulatedsemiconductor device.

In the foregoing exemplary embodiment, the seal tape 21 is attached inadvance to the respective lower surfaces of the inner leads 12 of theleadframe before the resin encapsulation process step. Instead ofattaching the tape to the leadframe this way, the seal tape 21 may beplaced on a molding die assembly and the leadframe may be adheredthereto. In such a case, the seal tape can be reeled off and supplied tothe molding die assembly as will be described later. As a result, theprocess can be further simplified.

Also, in this embodiment, a manufacturing process, in which resinencapsulation is performed with the seal tape attached to the back ofthe leadframe, has been exemplified. However, the method of the presentinvention is not limited to a semiconductor device including aleadframe. A technique of using a seal tape during a resin encapsulationprocess step, which is a basic concept of the present invention, isbroadly applicable to any resin encapsulation process step for asemiconductor device incorporating a semiconductor chip and includingsome members to be molded with resin. Thus, this technique is applicableto a resin encapsulation process step for a semiconductor device of aTAB or substrate type.

EMBODIMENT 2

Next, a second embodiment of the present invention will be described.FIG. 9 is a cross-sectional view illustrating a resin-moldedsemiconductor device of a substrate-bonded type according to thisembodiment.

As shown in FIG. 9, the resin-molded semiconductor device of thisembodiment is of a substrate-bonded type such as a BGA (ball grid array)type. The device includes: a substrate 24 made of single- ormultiple-layered glass epoxy plastic or ceramic; a semiconductor chip 25mounted on the substrate 24; and metal fine wires 26 for electricallyconnecting interconnects (not shown) formed on the upper surface of thesubstrate 24 to electrode pads (not shown) of the semiconductor chip 25.And over the upper surface of the substrate 24, the semiconductor chip25, interconnects and metal fine wires 26 are molded with an insulatingresin encapsulant 27. On the back of the substrate 24, externalelectrode pads (lands) 28 are formed. The interconnects on the uppersurface of the substrate 24 are connected to the external electrode pads(lands) 28 on the back surface of the substrate 24 by way of throughholes or via holes.

In this embodiment, ball electrodes 29, which are made of a conductivematerial for bonding the substrate 24 to an external board, are providedfor the external electrode pads 28. However, the ball electrodes 29 donot have to be provided. Also, the substrate 24 may be a thin polyimidefilm, for example.

According to this embodiment, the assembly is transfer-molded with aresin encapsulant while a seal tape is attached to the back of thesubstrate 24 during a resin encapsulation process step as will bedescribed later. Thus, it is possible to prevent the resin encapsulant27 from overflowing to reach the external electrode pads 28.Consequently, a surface to be connected to a motherboard can be freefrom resin bur, which would otherwise be formed on the externalelectrode pads 28, and the reliability in connecting with the ballelectrodes 29 interposed can be improved.

Next, a method for manufacturing the resin-molded semiconductor deviceof this embodiment will be described with reference to the drawings.FIGS. 10 through 12 are cross-sectional views illustrating, on astep-by-step basis, a manufacturing process for the BGA-typeresin-molded semiconductor device of this embodiment.

First, in the process step shown in FIG. 10(a), interconnects (notshown) are formed on the substrate 24, which is a single- ormultiple-layered glass epoxy plastic or ceramic plate. Through holes orvia holes are formed in the substrate 24. And the external electrodepads 28 are formed on the back of the substrate 24. Thereafter, thesemiconductor chip 25 is bonded at a predetermined position on thesubstrate 24 with a die-bonding member, for example, and theinterconnects on the substrate are connected to electrode pads (notshown) on the semiconductor chip with the metal fine wires 26.

Alternatively, the semiconductor chip 25 may be mounted onto thesubstrate 24 in a facedown manner shown in FIG. 10(b). In such a case,the interconnects on the substrate 24 are ordinarily bonded to theelectrode pads on the semiconductor chip 25 with metal balls 30 likebumps. As the case may be, the interconnects on the substrate 24 and theelectrode pads on the semiconductor chip 25 are alloyed and directlybonded to each other. The subsequent process steps will be described onthe supposition that the bonding structure shown in FIG. 10(a) has beenadopted here.

Next, in the process step shown in FIG. 11, resin encapsulation isperformed using a molding die assembly 31, consisting of lower and upperdies 31 a and 31 b, to mold the semiconductor chip 25, interconnects,and metal fine wires 26 over the substrate 24. In this step, before theresin encapsulation is performed, a first seal tape 32 a is attached tothe back of the substrate 24, i.e., to the upper surface of the lowerdie 31 a of the molding die assembly 31, thereby adhering the seal tape32 a to the lower surfaces of the external electrode pads 28 of thesubstrate 24. In this case, the pressure applied to the die assemblyforces the external electrode pads 28 into the seal tape 32 a. As aresult, the seal tape 32 a adheres to the back of the substrate 24 andto lower surfaces of the external electrodes 28. In addition, a secondseal tape 32 b is also adhered to the lower surface of the upper die 31b of the molding die assembly 31. By transfer-molding the assembly withthe resin encapsulant 27 in such a state, only the regions surroundingthe semiconductor chip 25 can be molded with the resin over the uppersurface of the substrate 24 and the overflow of the resin encapsulant tothe back of the substrate 24 can be prevented. And as described above,it is possible to prevent the resin bur from being formed on theexternal electrode pads 28 on the back of the substrate 24.

Also, since not only the first seal tape 31 a but also the second sealtape 32 b are used, the resin encapsulant 27 can be advantageouslyreleased from the upper die 31 b easily.

According to such a resin encapsulation technique, resin encapsulationis performed with pressure applied to the substrate 24 through themolding die assembly 31. Since pressure is herein applied to thestructure with the substrate 24 interposed between the first and secondseal tapes 32 a and 32 b, the force applied to the substrate 24 can becushioned and the fracture or deformation of the substrate 24 can beadvantageously prevented during the resin encapsulation.

Finally, in the process step shown in FIG. 12, the resin-moldedassembly, in which the regions surrounding the semiconductor chip 25over the substrate 24 are molded with the resin encapsulant 27, isreleased from the molding die assembly 31. As a result, a resin-moldedpackage, in which no resin encapsulant has reached the externalelectrode pads 28 on the back of the substrate 24, is obtained.

If the ball electrodes 29 (indicated by the phantom lines) are providedfor the external electrode pads 28 on the back of the substrate 24, aresin-molded semiconductor device of a BGA type can be obtained.Alternatively, if these external electrode pads 28 have been formed witha relatively large thickness, then the external electrode pads 28 may beused as external terminals as they are without forming the ballelectrodes 29 thereon.

As can be understood, in the method for manufacturing a BGA-typeresin-molded semiconductor device according to this embodiment, thefirst and second seal tapes 32 a and 32 b are used. By utilizing theelasticity thereof, deformation of the substrate 24 within the moldingdie assembly can be suppressed, and deposition of the resin encapsulantor foreign particles on the external electrode pads 28 of the substrate24 can be prevented.

Of the first and second seal tapes 32 a and 32 b, the first seal tape 32a is not always required. Even if only the second seal tape 32 b isprovided, it is also possible to prevent the overflow of the resinencapsulant to the sides or back of the substrate 24, since the secondseal tape 32 b is in contact with the upper surface of the substrate 24.

Furthermore, the seal tape 32 a does not have to be adhered to theentire back face of the substrate 24. The seal tape 32 a is onlyrequired to adhere to at least the lower surfaces of the externalelectrode pads 28.

EMBODIMENT 3

Next, a third embodiment of the present invention will be described.FIG. 13 is a cross-sectional view illustrating a resin-moldedsemiconductor device according to this embodiment. The resin-moldedsemiconductor device of this embodiment includes: a radiator plate; anda semiconductor chip incorporating a device generating a relativelylarge quantity of heat, e.g., a high-power transistor.

As shown in FIG. 13, the semiconductor device of this embodimentincludes: a bed 33, or a support for a leadframe; a semiconductor chip34 bonded on the bed 33 with a die-bonding member; a metal terminal 35of the leadframe; a metal fine wire 36 for electrically connecting themetal terminal 35 to the semiconductor chip 34; and a radiator plate 37for supporting the bed 33 thereon. In this structure, all the membersare entirely molded with an insulating resin encapsulant 38, except forthe bottom of the radiator plate 37 and part of the metal terminal 35protruding out of the resin encapsulant 38 as an external terminal. Thatis to say, the upper and side faces of the radiator plate 37, bed 33,semiconductor chip 34, metal fine wire 36 and the other part of themetal terminal 35 are molded with the resin encapsulant 38.

According to this embodiment, the assembly is transfer-molded with aseal tape attached to the back of the radiator plate 37 during a resinencapsulation process step as will be described later. Thus, it ispossible to prevent the resin encapsulant 38 from overflowing to reachthe back of the radiator plate 37 and forming resin bur thereon.Accordingly, the radiating face (back surface) of the radiator plate 37can maintain it function. That is to say, its function of dissipatingthe heat, which has been generated from the semiconductor chip of thesemiconductor device, to the outside can be maintained and improved.

Next, a method for manufacturing the resin-molded semiconductor deviceof this embodiment will be described with reference to the drawings.FIGS. 14 through 18 are cross-sectional views illustrating, on astep-by-step basis, a manufacturing process for the resin-moldedsemiconductor device including a radiator plate according to thisembodiment.

First, in the process step shown in FIG. 14, a lead-frame, including thebed 33, or a support for a semiconductor chip, and the metal terminal35, is prepared. The semiconductor chip 34 is bonded onto the uppersurface of the bed 33 with a die-bonding member. Then, the semiconductorchip 34 is connected to the metal terminal 36 with the metal fine wire36.

Next, in the process step shown in FIG. 15, the radiator plate 37 isbonded onto the back of the bed 33. Alternatively, the bed 33 may alsobe formed with an increased thickness so as to function as a radiatorplate by itself.

Then, in the process step shown in FIG. 16, the seal tape 39 is adheredto the back of the radiator plate 37. In this case, the radiator plate37 with the seal tape 39 adhered thereto may be placed into a moldingdie assembly. Alternatively, the back of the radiator plate 37 may beadhered to the seal tape 39 by attaching in advance the seal tape 39 tothe molding die assembly, more specifically onto the lower die, and thenmounting the radiator plate 37 onto the lower die.

Subsequently, in the process step shown in FIG. 17, the bed 33,semiconductor chip 34, metal fine wire 36 and part of the metal terminal35 are molded with the insulating resin encapsulant 38 while the sealtape 39 is adhered to the back of the radiator plate 37. In this case,the bottom of the radiator plate 37 and the other part of the metalterminal 35 are exposed out of the resin encapsulant 38.

Finally, in the process step shown in FIG. 18, the seal tape 39 ispeeled off from the back of the radiator plate 37 and the metal terminal35 is folded, thereby completing a resin-molded semiconductor deviceshown in FIG. 18, in which the back of the radiator plate 37 is exposed.

In the method for manufacturing the resin-molded semiconductor deviceincluding a radiator plate according to this embodiment, the seal tape39, which is adhered to the back of the radiator plate 37, is usedduring the resin encapsulation process step, thereby preventing theoverflow of the resin encapsulant onto the back of the radiator plate 37and the formation of resin bur thereon. In other words, since the backof the radiator plate 37 can be exposed without fail, a resin-moldedsemiconductor device can be obtained without lessening the radiationeffect of the radiator plate 37. Also, since the resin encapsulation isperformed with the seal tape 39 adhered to the back of the radiatorplate 37, part of the seal tape 39 is forced inward to partially coverthe sides of the radiator plate 37. As a result, the radiator plate 37slightly protrudes out of the back of the resin encapsulant after theresin encapsulation is over. Accordingly, in mounting such aresin-molded semiconductor device onto a motherboard, the entire backsurface of the radiator plate 37 can be in contact with the motherboardwithout fail, thus enhancing the radiation effect.

EMBODIMENT 4

Next, a fourth embodiment of the present invention will be describedwith reference to the drawings. FIG. 19 is a cross-sectional viewillustrating a resin-molded semiconductor device, like a CCD package,according to this embodiment.

As shown in FIG. 19, the resin-molded semiconductor device of thisembodiment includes: a resin package 41 with an opening in the upperpart thereof and a recess 42 provided within the opening; a solid-stateimaging device 40 bonded onto the bottom of the recess 42 of the resinpackage 41 with a die-bonding member; inner leads 43 provided near therecess 42 of the resin package 41; outer leads 46, which are connectedto the respective inner leads 43 and extend outward through the resinpackage 41; and metal fine wires 44 for electrically connectingelectrode pads (not shown) on the solid-state imaging device 40 to theinner leads 43 on the resin package 41. Also, the opening of the resinpackage 41 is sealed with sealing glass 45. The outer leads 46,protruding out of the resin package 41, are folded downward. It shouldbe noted that the resin package 41 is a package that has been integrallytransfer-molded with an insulating resin.

In the resin-molded semiconductor device according to this embodiment,the resin package 41 is formed by performing transfer-molding with aseal tape attached onto the inner leads 43 during a resin encapsulationprocess step as will be described later. Thus, no resin bur is formed onrespective upper surfaces of the inner leads 43, but these surfaces areexposed. Accordingly, in this resin-molded semiconductor device, theinner leads 43 can be connected to the solid-state imaging device 40 viathe metal fine wires 44 with more reliability.

Next, a method for manufacturing the resin-molded semiconductor deviceaccording to this embodiment, like a CCD package, will be described withreference to the drawings. FIGS. 20 through 22 are cross-sectional viewsillustrating, on a step-by-step basis, a manufacturing process for theresin-molded semiconductor device according to this embodiment.

First, in the process step shown in FIG. 20, a lead assembly, includinginner and outer leads 43 and 46, is prepared. Before the resin packageis molded, the seal tape 47 is attached or adhered to those portions ofthe lead assembly to be the inner leads 43, thereby preventing theoverflow of the resin encapsulant onto the upper surfaces of the innerleads 43. Then, the respective members are transfer-molded with a resinwithin a molding die assembly consisting of upper and lower dies 51a and51b, thereby forming the resin package 41. FIG. 20 illustrates a statewhere the resin package 41 has already been formed and the respectivesurfaces of the inner and outer leads 43 and 46 are covered with theseal tape 47.

Then, in the process step shown in FIG. 21, the seal tape 47 is peeledoff, thereby obtaining a resin package 41, in which the respective uppersurfaces of the inner leads 43 are exposed without fail. At an elevatedtemperature, the seal tape 47 adheres to the inner leads 43 withoutforming any gap therebetween. Thus, on the exposed surfaces of the innerleads 43, from which the seal tape 47 has been peeled off, no foreignparticles, such as resin bur of the resin encapsulant, are deposited.

Subsequently, in the process step shown in FIG. 22, the solid-stateimaging device 40 is bonded onto the bottom of the recess 42 providedwithin the resin package 41. Electrode pads on the solid-state imagingdevice 40 are connected to the inner leads 43 with the metal fine wires44. After the opening of the resin package 41 has been sealed with thesealing glass 45, the outer leads 46 are folded. The outer leads 46 maybe folded into a desired shape depending on the type of thesemiconductor device.

A resin encapsulation technique using a seal tape according to thisembodiment is particularly suitable for manufacturing a semiconductordevice including a resin package with an opening in the upper partthereof, e.g., an optical semiconductor device like a CCD or a hologram.In particular, remarkable effects can be attained if this embodiment isapplied to molding a resin package including leads.

Another application of this embodiment will be briefly described. Inmanufacturing a component, such as an LED, the package of which shouldhave required color or transparency, resin encapsulation can beperformed effectively by attaching a seal tape to a molding die assemblyin advance such that foreign particles or dirt involved with the moldingdie assembly are not transferred to the package. As a result, anexcellent package can be formed.

Industrial Applicability

The resin-molded semiconductor device and the method for manufacturingthe same according to the present invention are applicable to all sortsof electronic equipment using a semiconductor integrated circuit made upof various types of transistors.

What is claimed is:
 1. A method for manufacturing a resin-moldedsemiconductor device, characterized by comprising: a first step ofpreparing a leadframe, the leadframe including: inner leads; a die padwith externals smaller than those of a semiconductor chip to be mountedthereon; and support leads for supporting the die pad, each said supportlead being provided with a stepped portion for elevating the die padabove the inner leads; a second step of bonding the semiconductor chiponto the upper surface of the die pad of the leadframe; a third step ofbonding the semiconductor chip onto the upper surface of the die pad ofthe leadframe; a third step of connecting the semiconductor chip to theinner leads with metal fine wires after the second step has beenperformed; a fourth step of placing a seal tape between a molding dieassembly and the leadframe such that the seal tape adheres only to theback surface of the inner leads after the third step has been performed,a fifth step of encapsulating using a resin encapsulant with respectivetips of the inner leads of the leadframe pushed downward to press asurface of the seal tape, which is in contact with respective backsurfaces of the inner leads, against the die assembly and thereby forcethe inner leads into the seal tape, after the fourth step has beenperformed; and a sixth step of removing the seal tape to protruderespective lower parts of the inner leads out of the resin encapsulantand thereby form external electrodes after the fifth step has beenperformed.
 2. The method for manufacturing a resin-molded semiconductordevice of claim 1, characterized in that in the first step, theleadframe prepared has been plated with metal layers of nickel (Ni),palladium (Pd) and gold (Au).
 3. The method for manufacturing aresin-molded semiconductor device of claim 1, characterized in that inthe second step, the seal tape attached has such a thickness ascorresponding to a desired value, which is equal to a height of lowersurfaces of the inner leads protruding downward from the back surface ofthe resin encapsulant after the resin encapsulation.
 4. The method formanufacturing a resin-molded semiconductor device of claim 1,characterized in that in the fifth step, encapsulation is performed sothat the resin encapsulant covers the back surface of the die pad.
 5. Amethod for manufacturing a resin-molded semiconductor device,characterized by comprising: a first step of bonding a semiconductorchip onto the supper surface of a substrate, the upper surface of thesubstrate being provided with interconnects, the back surface of thesubstrate being provided with external electrodes; a second step ofelectrically connecting the semiconductor chip to the interconnects onthe upper surface of the substrate with metal fine wires; a third stepof placing a seal tape between a molding die assembly and the substratesuch that the seal tape adheres only to the back surface of thesubstrate after the second step has been performed; a fifth step ofencapsulating using a resin encapsulant with the substrate pusheddownward to press a surface of the seal tape, which is in contact withthe back surface of the substrate, against the die assembly and therebyforce at least part of the external electrodes of the substrate into theseal tape, after the third step has been performed; and a sixth step ofremoving the seal tape after the fifth step has been performed.
 6. Themethod for manufacturing a resin-molded semiconductor device of claim 5,characterized in that in the fifth step, encapsulation is performed sothat the resin encapsulant covers the back surface of the die pad.
 7. Amethod for manufacturing a resin-molded semiconductor device,characterized by comprising: a first step of bonding a semiconductorchip onto the upper surface of a bed of a support member, the supportmember including leads and the bed; a second step of bonding a radiatoronto the back surface of the bed of the support member; a third step ofelectrically connecting the semiconductor chip to the leads; a fourthstep of adhering a seal tape to the back surface of the radiator afterthe third step has been performed; a fifth step of encapsulating using aresin encapsulant with the support member pushed downward to press asurface of the seal tape, which is in contact with the back surface ofthe radiator, against a die assembly and thereby force the back surfaceof the radiator into the seal tape, after the fourth step has beenperformed; and a sixth step of removing the seal tape after the fifthstep has been performed.
 8. The method for manufacturing a resin-moldedsemiconductor device of claim 7, characterized in that in the fifthstep, encapsulation is performed so that the resin encapsulant coversthe back surface of the die pad.